When multimeters go boom

Ever wondered how expensive versus cheap multimeters hold up to abuse? [Dave] gives us a pretty good idea by, well, blowing them up. He’s using a capacitor bank to put roughly 4.2 KiloVolts into the poor little meters. If you absolutely must skip to the multimeters, go to about 5:00. You really will miss out on some good stuff though.

it’s totally expected :D The purpose was to show the difference between the types of failure… smoke and fire, in the case of the cheap meters, versus a little pop, in the case of the cat-3 rated meters.

I see nothing wrong with these cheap meters. Yes, I’m aware that if you overload something it might go pop, but the expensive and cheap beters both did that, so no real difference there.

What other disadvantages are there of cheap meters? Most of them seem to have all the extra functions now. (ie. transistor testing and temperature sensing). Accuracy may be an issue, but I think most claim +-0.5% to +-1.5% on their datasheets, and for most stuff I do that is plenty good enough.

I do find the leads of cheap multimeters keep breaking, but I suspect the expensive ones would do that if I treated them the same…

No real difference? I would prefer to be holding a quality DMM if I accidentally shorted a busbar to ground (by for example measuring current instead of voltage). The cheap ones blew up, the expensive ones had their protection components pop the way they should. Seriously if you are working with electrical installation and using a cheap multimeter then you are asking to have your digits ripped off.

This is neat, I was introduced to this when I was working for the local college auto shop. I was investigating why the fuses in a Fluke88 cost $15 apiece (the students were regularly blowing them). The answer was in the Fluke adverts, the fuses are full of sand, they are supposed to fuse into glass and prevent a plasma fireball at 15kv.

It was accompanied by a ~16″ diameter plasma explosion picture.

I made up some test leads with standard 3amp blade fuses for those meters.

I usually wait for the $1/$2/$3 multimeters at Harbor Freight, compared to the Flukes they were plenty accurate. Since I live in CA I am not going to be using them below freezing, or even near. Any testing I do is going to be checking a relative measurement anyway, so as long as it is reasonably accurate I am fine.

I would venture to say if you don’t know why you need the protection then you probably do not need it. If you don’t want the accuracy, fine, but I would surely hate it for you if you found out after the fact that you did need it. It is nice that a unit will simply blow up and become useless, rather than blow up and become a conduit for your hand to do the same. The point of the good meters is not for the meter to survive the shock, the point is that it allows you the chance to survive it.

And if you do survive it, I bet there would be no limit you would pay to get your hand back. Trust me, the meter is cheap in comparison to your health and well being.

Sorry for the split post. Watch the video again, you will see the cheap meters continue to pop, even after the first jolt. Guess what the new conduit would have been? The good meters die the first jolt and go to heaven, and they don’t take you with them.

OMG please tell me you don’t believe that these guys are mentally ok.
They get off on blowing up electronic equipment instead of going out get some cunt or drink or do drugs or whatever else, this is just SICK…

Response time; I’ve got a cheap Crapsman meter that I can’t use to check to see if I’m getting a firing signal that’s only there for a second because it takes a second or so to decide what to display; my nice fluke shows me what it’s reading almost instantaneously.

That could mean the difference between ordering a mainboard and not fixing anything or ordering an inverter and solving the problem.

I agree that the cheap ones held up well enough, so they had a bit of smoke and popped a bit, that only help to alert you and it to ‘auto disengage’, and the flashes stayed in the case, and the case did not catch fire or had parts pierce it.
And seeing they all use meter-on-a-chip design it’s not THAT bad with accuracy, although the supporting components like reference resistors and such might be not that great and cause problems, but all in all I was surprised how well they dealt really, and how fairly OK their readings are in practice.

If I have say 50 MJ from a grounded busbar decide that the laws of physics must be obeyed, that cheapo is going to pretty much explode (any object can only withstand a certain amount of any type of energy at a given moment, too much and catastrophic failure).
Problem is conservation of energy. The energy has to go somewhere and it’s going to be into my hand that will QUICKLY lose some fingers if not outright destroyed.
Now I’ve got FIVE finger.

Scenario 2
I’ve got TEN fingers.

Using a good $400 Fluke Professional Series.

If I have say 50 MJ from a grounded busbar decide that the laws of physics must be obeyed, that limit circuit in that Fluke is going to EAT THAT ENERGY LIKE A FAT BOY IN A DONUT FACTORY.
Conservation of energy is not a problem. The energy has to go somewhere and it’s going to be into the fuses, MOSFETs, other safety goodies.

Now I’ve STILL got TEN fingers.

I love my fingers, been quite attached to them all my life. Hope to keep them until they day I die doing some insane Jaquline Bauer shit!

PS – Just grabbed the energy numbers out of thin air, too lazy to find breakdown voltage of human hands in this scenario… but I think my point is made.

Everyone of you need to get off your high horse. If you are working with high voltages, get a professional meter. Otherwise, the el cheapo meter will do fine. I’ve shorted out 120 & 220 volts (single phase) with an el cheapo and yes, the meter became unusable, but it was only $15.00 and I will never be working with anything near even 600 volts so they work fine.

Anyone that uses an inaccurate Home Depot cheapo meter does not get to complain about people using Arduinos. Real electronics people may use ISPs, but real electronics people also understand the value of a good multi meter.

If your multi meter has a transistor tester function, you just might be an artist using an Arduino.

Useless destruction…
What was learned from this:
The expensive ones, which are certified to provide protection, fail safely if used out of spec. That’s good, but expected.
The cheap ones, not promising protection, will just fail if used out of spec. That’s not so good, but again, expected. Even if they did exhibit a safer behavior in this test, I wouldn’t rely on it afterwards.
It would have been more interesting to see if they are safe to use up to their rated voltage, instead of senselessly blowing them up by exceeding the rating wildly.

I find those cheap meters quite useful actually. Of course they are NOT Flukes or anything similar. Of course you’ll get what you pay for, but still…
In my opinion the worst of the cheapos are those $2 ones. The range switch are simply too crappy and you can’t rely on the ”accuracy” (in reality it’s non-existent) at all. But, some will find those meters useful too, so I can’t judge anyone.
One of the better are the ”Fluke” copies on e-bay, like the ”VC97” and ”VC99”. Bought the VC97 6 months ago or so and compared it to a bench multimeter that is calibrated regularly. Not bad accuracy at all – absolutely not(except the capacitance measurement under 0.01uF), and more than good enough for hobbyist use as long as you’re not pushing their limits, like measuring near 1kV.

Watch out for fake multimeters coming from China. A lot are sold on eBay by chinese in, say the USA or other western countries who masquerade as local sellers, but are in fact getting the faked goods from their criminal friends in China. It’s not just multimeters, the chinese fake everything!